New surveillance tech links your phone to your license plate
New surveillance tech links your phone to your license plate
新型监控技术将你的手机与车牌关联起来
Imagine that you share a ride to work with the same colleague most mornings. As it passes by a license plate reader, the camera records the car, which can be linked through vehicle records to its registered owner. Beside it, another sensor detects signals broadcast by devices traveling nearby, such as your phone and your colleague’s smartwatch. After enough trips, software may treat some of those devices as a recurring electronic signature associated with the vehicle. 想象一下，你每天早上都和同一位同事拼车上班。当车辆经过车牌识别器时，摄像头会记录下这辆车，并通过车辆记录将其与车主关联起来。与此同时，另一个传感器会检测附近设备（如你的手机和同事的智能手表）广播的信号。经过多次行程后，软件可能会将其中一些设备视为与该车辆相关的“重复电子签名”。
Weeks later, one of the same device signals appears alongside a different car connected to an investigation. The signal itself may not contain its owner’s name, but its previous association with a known vehicle gives investigators another clue they can use to work out who was carrying the device. 几周后，同一个设备信号出现在另一辆与某项调查有关的汽车旁。信号本身可能不包含机主的姓名，但它之前与已知车辆的关联为调查人员提供了另一条线索，帮助他们推断出是谁携带了该设备。
SignalTrace, a system marketed by the security company Leonardo, is designed to work alongside automatic license plate readers. The company says it can recognize groups of consumer devices that regularly move together, then associate them with license plate records and time-stamped locations. The pattern can then be searched even when a police investigator does not know the plate number. SignalTrace 是由安全公司 Leonardo 销售的一套系统，旨在与自动车牌识别器配合使用。该公司表示，该系统可以识别经常一起移动的消费设备群，然后将它们与车牌记录和带有时间戳的位置信息关联起来。即使警察调查员不知道车牌号码，也可以搜索这种模式。
I am a researcher who studies the intersection of data governance, digital technologies, and governments, including surveillance technologies. I see that SignalTrace could further shift how police conduct investigations, putting emphasis on people’s movements and associations before their identities are known. 我是一名研究数据治理、数字技术与政府（包括监控技术）交叉领域的研究员。我认为 SignalTrace 可能会进一步改变警察进行调查的方式，在确认身份之前，将重点放在人们的行踪和社交关联上。
SignalTrace is a tested and marketed capability, but not yet an established police practice. One report indicates that several of the devices are installed in Oxon Hill, Maryland, and the company’s predecessor technology appears on an official New York state contract price list. SignalTrace 是一项经过测试并已上市的功能，但尚未成为警察的常规办案手段。一份报告显示，马里兰州奥克森山（Oxon Hill）安装了多台此类设备，且该公司的前身技术出现在纽约州的官方合同价格清单上。
A narrow definition of identification
对“身份识别”的狭隘定义
Leonardo’s new explanatory sheet states that SignalTrace “does not identify people.” It says the system “only collects electronic signatures” from signals already being broadcast, such as Bluetooth or radio frequency identification tags. Those signatures, by themselves, do not disclose a person’s identity. The company says the output must be corroborated through ordinary investigative methods. Leonardo 的新说明书称，SignalTrace “不会识别个人”。它表示，该系统“仅收集”已在广播的信号（如蓝牙或射频识别标签）中的“电子签名”。这些签名本身并不会泄露个人的身份。该公司表示，其输出结果必须通过常规调查方法进行核实。
That description relies on a narrow meaning of identity, however. A sensor may not pull a legal name from a phone, but police could still work out who likely owns the device by linking its signal to other records. For example, the same signal might repeatedly appear with a car registered to one person, outside that person’s home, or alongside another device already connected to a known subject. That means a person could become part of an investigation because of where their device repeatedly appeared and who it appeared near, even if the police had no reason to suspect that person at the outset. 然而，这种描述依赖于对“身份”的狭隘理解。传感器可能无法从手机中提取法定姓名，但警方仍可以通过将信号与其他记录关联来推断出设备的所有者。例如，同一个信号可能反复出现在某人名下的汽车旁、该人的住所外，或与另一个已知的调查对象设备在一起。这意味着一个人可能会因为其设备反复出现的位置以及它出现在谁的附近而被卷入调查，即使警方最初并没有理由怀疑此人。
Leonardo’s SignalTrace product page says the system stores electronic fingerprints for later queries and can recognize a vehicle without seeing its license plate. A separate product sheet says the technology helps identify suspects through the mix of devices they carry. The patent behind the system describes targets that may be people or vehicles. It also describes searchable signatures that can be correlated with visual identifiers and used to track a target across locations. Leonardo 的 SignalTrace 产品页面称，该系统存储电子指纹以供后续查询，并且无需看到车牌即可识别车辆。另一份产品说明书称，该技术通过分析嫌疑人携带的设备组合来帮助识别他们。该系统背后的专利描述了目标可能是人或车辆。它还描述了可搜索的签名，这些签名可以与视觉标识符相关联，并用于跨地点追踪目标。
SignalTrace may begin with a nameless pattern, but its value comes from recognizing that pattern again and connecting it to information that police already possess. Once an officer links a recurring signature to a license plate record or case file, the absence of a name in the original signal offers little protection. SignalTrace 可能始于一个无名的模式，但其价值在于再次识别该模式，并将其与警方已掌握的信息联系起来。一旦警官将一个重复出现的签名与车牌记录或案件档案关联起来，原始信号中缺乏姓名这一事实就几乎无法提供任何保护。
A nameless identifier can still be personal
无名标识符仍可能涉及个人隐私
Federal privacy guidance does not limit identifying information to names. The National Institute of Standards and Technology defines personally identifiable information as data that can distinguish or trace a person’s identity, either alone or when combined with linkable information. The key question is whether data can single someone out and follow them over time. 联邦隐私指南并未将识别信息局限于姓名。美国国家标准与技术研究院（NIST）将“个人身份信息”定义为：能够单独或结合可关联信息来区分或追踪个人身份的数据。关键问题在于，这些数据是否能够锁定某人并对其进行长期追踪。
Research on mobility data—records collected from people’s mobile devices indicating where they went—helps explain the risk. A study in the journal Scientific Reports examined 15 months of records covering 1.5 million people. Four time-and-place points were enough to uniquely identify 95% of the people in the dataset. The study did not test SignalTrace, but it shows why repeated movement can make a supposedly anonymous record distinctive. 关于移动数据（从人们移动设备收集的行踪记录）的研究有助于解释这种风险。《科学报告》期刊上的一项研究调查了涵盖 150 万人的 15 个月记录。研究发现，仅需四个“时间-地点”点，就足以唯一识别数据集中 95% 的人。该研究虽然没有测试 SignalTrace，但它揭示了为什么重复的移动轨迹可以使原本匿名的记录变得具有唯一性。
The Supreme Court has recognized that phone location records can reveal far more than movement. In Carpenter v. United States, the court concluded that people have a reasonable expectation of privacy in the record of their physical movements. The court extended that reasoning in its June 2026 decision in Chatrie v. United States. Police investigating a bank robbery had used a type of warrant to obtain anonymized location records for phones near the bank, narrowed the list based on their movements, and eventually obtained the names of several users. The justices held that obtaining location data constituted a Fourth Amendment search. It also noted that even short-term monitoring can reveal political, family, and other associations. 最高法院已承认，手机位置记录揭示的信息远不止行踪。在“卡彭特诉美国案”（Carpenter v. United States）中，法院裁定人们对其物理行踪记录享有合理的隐私期待。法院在 2026 年 6 月对“查特里诉美国案”（Chatrie v. United States）的裁决中扩展了这一推理。警方在调查一起银行抢劫案时，使用搜查令获取了银行附近手机的匿名位置记录，根据其移动轨迹缩小了名单范围，并最终获得了几名用户的姓名。大法官们裁定，获取位置数据构成了第四修正案意义上的“搜查”。法院还指出，即使是短期的监控也可能揭示政治、家庭和其他社交关联。
The ruling does not determine whether police collection of wireless signals detected by SignalTrace would also count as a search. The Chatrie case involved location records, while SignalTrace is designed to detect signals broadcast from nearby devices. But the two technologies raise a related question: What Fourth Amendment protections apply when police begin with unidentified devices and use their movements to determine who might be connected to an event or another person? 该裁决并未确定警方收集 SignalTrace 检测到的无线信号是否也算作“搜查”。“查特里案”涉及的是位置记录，而 SignalTrace 旨在检测附近设备广播的信号。但这两种技术提出了一个相关问题：当警方从身份不明的设备入手，并利用其移动轨迹来确定谁可能与某事件或某人有关联时，第四修正案的保护措施应如何适用？
When proximity becomes an investigative lead
当“邻近性”成为调查线索
The deeper issue is association. A recurring cluster may reflect a family routine or shared commute. It may also capture fellow protesters or pass… 更深层的问题在于“关联”。一个重复出现的设备集群可能反映了家庭作息或共同通勤。它也可能捕捉到抗议同伴或路人……